Adaptive antenna reception device having preferable reception quality of directivity beam from the initial stage

ABSTRACT

An adaptive antenna reception device is disclosed in which a directional beam having excellent reception characteristics can be quickly and easily obtained from the start by selecting an initial beam direction of signal processors that are to begin determination of weight that uses time averaging based on the reception quality and the arrival direction in which the reliability is high for an incoming wave that is received in each signal processor in which sufficient averaging time has been secured. An arrival direction detection unit detects the arrival direction of an incoming wave that is received in each signal processor from weight that is determined by each signal processor in which at least a prescribed time interval has been secured for the averaging time for finding a time average. A SIR measurement unit finds the reception quality of a signal of an incoming wave that is received by weighting and synthesizing in each signal processor in which at least a prescribed time interval has been secured for the averaging time. An information collection/selection processor, based on each arrival direction and each reception quality in each signal processor in which at least a prescribed time interval has been secured for the averaging time, selects the initial beam direction in signal processors that are to begin determination of weight using time averaging.

TECHNICAL FIELD

The present invention relates to an adaptive antenna reception methodfor weighting each of the antennas that make up an adaptive antenna toreceive a signal with superior characteristics, and to a device thatuses such a method.

BACKGROUND ART

In a mobile communication system according to the CDMA (Code DivisionMultiple Access) method, a radio base station simultaneously receivesuser signals from a plurality of mobile stations, and signals of otherusers therefore interfere with the signal of a particular user. Anadaptive antenna is used to receive a desired user signal at a highergain.

An adaptive antenna is composed of a plurality of antennas and controlsamplitude and phase in accordance with a complex number weight that isconferred to the signals that are received by each of the antennas toform directivity. An adaptive antenna is thus capable of suppressingother user signals that constitute interference and of effectivelyreceiving a desired user signal.

Two methods are typically used for determining the weight that isconferred to each antenna of an adaptive antenna.

In one method, weighting is determined by performing feedback controlusing an algorithm that follows the MMSE (Minimum Mean Square Error)standard. An adaptive updating algorithm such as an RLS (Recursive LeastSquare) algorithm of the sequential weight updating type or arepresentative LMS (Least Mean Square) algorithm is used.

In contrast, the other method is the open-loop control method that isthe object of the present invention. According to this method, anarrival direction estimation algorithm such as a MUSIC (MUltiple SignalClassification) algorithm or an ESPRIT (Estimation of Signal Parametersvia Rotational Invariance Techniques) algorithm is used to estimate thearrival direction of a desired wave based on the signals received inantennas, and the weight of each antenna is then determined inaccordance with this direction. A method of determining weight byopen-loop control is disclosed in, for example, JP 11-274976-A.

FIG. 1 is a block diagram showing an example of the configuration of anadaptive antenna reception device of the prior art that is described inJP 11-274976-A. In the adaptive antenna reception device that is shownin FIG. 1, N is the number of antennas that make up the adaptive antenna(where N is an integer equal to or greater than 2), and L is the numberof synthesized multi-paths (where L is a natural number). FIG. 1 showsthe circuit portion for receiving the user signal that is received fromthe mobile station of the k^(th) user (where k is a natural number).

Referring to FIG. 1, the adaptive antenna reception device includes:antennas 1 ₁-1 _(N), signal processors 2 ₁-2 _(L), adder 11, determiner12, and searcher 16. Fingers that correspond to each of the multi-pathsthat undergo rake synthesis are assigned to signal processors 2 ₁-2_(L). Signal processor 2 ₁ includes: delay unit 3 ₁, despreadingcircuits 4 ₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weightcalculation unit 6 ₁, transmission path estimation circuit 7 ₁, complexconjugate circuit 8 ₁, initial weight generation unit 9 ₁, andmultiplier 10 ₁. In addition, weight calculation unit 6 ₁ includes:signal common-mode average calculation unit 13 ₁, correlation detectionunit 14 ₁, and time average calculation unit 15 ₁.

Although not shown in the figure, the interiors of signal processors 2₂-2 _(L) have the same configuration as signal processor 2 ₁. Forexample, signal processor 2 ₂ is made up from: delay unit 3 ₂,despreading circuits 4 ₂₁-4 _(2N), weighting/synthesizing circuit 5 ₂,weight calculation unit 6 ₂, transmission path estimation circuit 7 ₂,complex conjugate circuit 8 ₂, initial weight generation unit 9 ₂, andmultiplier 10 ₂. In addition, weight calculation unit 6 ₂ includessignal common-mode average calculation unit 13 ₂, correlation detectionunit 14 ₂, and time average calculation unit 15 ₂.

Searcher 16 uses each of the signals that are received by N antennas 1₁-1 _(N) to detect the delay time of L multi-paths. Searcher 16 thenreports the timing information of the delay times that are used in eachfinger to delay units 3 ₁-3 _(L), weight calculation units 6 ₁-6 _(L),and initial weight generation units 9 ₁-9 _(L) of signal processors 2₁-2 _(L) that constitute each finger of rake synthesis. The N antennas 1₁-1 _(N) are arranged in proximity so as to have a high level ofcorrelation with each other, and as a result, the delay profiles of Nantennas 1 ₁-1 _(N) can be considered to be identical. Accordingly, thetiming information of the delay time of each multi-path can be used incommon for all of antennas 1 ₁-1 _(N).

Delay unit 3 ₁ delays each of the signals that are received by antennas1 ₁-1 _(N) in accordance with the timing information that has beenreported from searcher 16 and sends the signals to despreading circuits4 ₁₁-4 _(1N). Delay units 3 ₂-3 _(L) similarly delay each of the signalsthat have been received by antennas 1 ₁-1 _(N) in accordance with thetiming information that has been reported from searcher 16. In this way,signal processors 2 ₁-2 _(L) can each be placed in correspondence withthe L multi-paths.

Despreading circuits 4 ₁₁-4 _(1N) perform despreading of each of thereceived signals that have been delayed by delay unit 3 ₁ and send theresults to weighting/synthesizing circuit 5 ₁, weight calculation unit 6₁, and initial weight generation unit 9 ₁.

Initial weight generation unit 9 ₁ generates an initial weight for usewhen weight of sufficient accuracy cannot be obtained by weightcalculation unit 6 ₁ and sends the result to weighting/synthesizingcircuit 5 ₁.

Initial weight generation unit 9 ₁ is used when searcher 16 newlyassigns a finger to signal processor 2 ₁, or when sufficient averagingtime cannot be secured in weight calculation unit 6 ₁ of signalprocessor 2 ₁ to which a finger has been assigned. Averaging time is thetime that is used for finding the average for the variation value thatis the object of averaging. The average value in the averaging time ofthe variation value is found by averaging in the averaging time. Inaddition, initial weight generation unit 9 ₁ is also used when the pathtiming of a finger that is in use undergoes a large change.

FIG. 2 is a block diagram showing the configuration ofweighting/synthesizing circuit 5 ₁. Weighting/synthesizing circuit 5 ₁includes: multipliers 17 ₁-17 _(N), adder 18, and complex conjugatecircuits 19 ₁-19 _(N).

Complex conjugate circuits 19 ₁-19 _(N) of weighting/synthesizingcircuit 5 ₁ generate a complex conjugate of the weight that is generatedby weight calculation unit 6 ₁ or by initial weight generation unit 9 ₁and send this complex conjugate to multipliers 17 ₁-17 _(N).

Each of multipliers 17 ₁-17 _(N) multiplies received signals that haveundergone despreading by despreading circuits 4 ₁₁-4 _(1N) with thecomplex conjugates of weights that have been generated by complexconjugate circuits 19 ₁-19 _(N) that correspond to the signals and sendsthe results to adder 18.

Adder 18 synthesizes the outputs of multipliers 17 ₁-17 _(N) and sendsthe results to transmission path estimation circuit 7 ₁ and multiplier10 ₁ that are shown in FIG. 1.

Signal common-mode average calculation unit 13 ₁ of weight calculationunit 6 ₁ adds vectors of the symbols of each signal that has undergonedespreading by despreading circuits 4 ₁₁-4 _(1N) during the matchingphase, finds the average values of signals for each antenna, and sendsthe results to correlation detection unit 14 ₁. At this time, any numberof symbols may undergo vector addition, and any weight can be applied toeach symbol.

Correlation detection unit 14 ₁ uses the average value of each signalfrom signal common-mode average calculation unit 13 ₁ to findcorrelation between the received signal at the antenna that is thestandard and received signals at other antennas. For this purpose,correlation detection unit 14 ₁ multiples the complex conjugate of theaverage value of the signal that corresponds to the reference antenna bythe average values of signals for other antennas and sends thecorrelations that are the results of each multiplication to time averagecalculation unit 15 ₁.

Time average calculation unit 15 ₁ takes the mean in a prescribed timeinterval for each multiplication result from correlation detection unit14 ₁, finds the weight for each of antennas 1 ₁-1 _(N), and sends theresults to weighting/synthesizing circuit 5 ₁. There are a variety ofweight methods and time intervals for taking the mean in time averagecalculation unit 15 ₁, and the method and time interval can be freelyselected.

In this way, weighting/synthesizing circuit 5 ₁ uses the weight that hasbeen generated in weight calculation unit 6 ₁ to control and synthesizethe amplitude and phase of the signals received by antennas 1 ₁-1 _(N)and form the directivity by which a desired user signal can be receivedat high gain.

Transmission path estimation circuit 7 ₁ estimates the transmission pathdistortion based on the output signal of weighting/synthesizing circuit5 ₁ and sends the result to complex conjugate circuit 8 ₁.

Complex conjugate circuit 8 ₁ generates a complex conjugate of thetransmission path distortion that has been estimated by transmissionpath estimation circuit 7 ₁.

Multiplier 10 ₁ multiplies the complex conjugate of the transmissionpath distortion that has been generated by complex conjugate circuit 8 ₁by the output signal of weighting/synthesizing circuit 5 ₁ to compensatethe transmission path distortion.

Signals in which the transmission path distortion from each finger hasbeen compensated are similarly obtained by signal processors 2 ₁-2 _(L).

Adder 11 performs rake synthesis by adding the output signals of signalprocessors 2 ₁-2 _(L) and sends the synthesized output signal todeterminer 12.

Determiner 12 determines each symbol and supplies the reception symbolof k^(th) user as output.

FIG. 3 is a flow chart showing the operation when assigning fingers inthe adaptive antenna reception device that is shown in FIG. 1. Referringto FIG. 3, signal processors 2 ₁-2 _(L) first determine whether anassigned finger is a new finger or not (Step C1).

If the assigned finger is a new finger, signal processors 2 ₁-2 _(L) usethe initial weight that has been generated by initial weight generationunits 9 ₁-9 _(L) in weighting/synthesizing circuits 5 ₁-5 _(L) (StepC4).

If the assigned finger is not a new finger, signal processors 2 ₁-2 _(L)determine whether sufficient averaging time has been secured in signalcommon-mode average calculation units 13 ₁-13 _(L) and time averagecalculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L)(Step C2).

If sufficient averaging time of weight calculation units 6 ₁-6 _(L) hasnot been secured, signal processors 2 ₁-2 _(L) use the initial weightthat has been generated in initial weight generation units 9 ₁-9 _(L) inweighting/synthesizing circuits 5 ₁-5 _(L) (Step C4). On the other hand,if sufficient averaging time of weight calculation units 6 ₁-6 _(L) hasbeen secured, signal processors 2 ₁-2 _(L) use the weight that wasgenerated in time average calculation units 15 ₁-15 _(L) inweighting/synthesizing circuits 5 ₁-5 _(L) (Step C3).

FIG. 4 is a flow chart showing the operations at the time of change ofpath timing of a finger in the adaptive antenna reception device that isshown in FIG. 1. Referring to FIG. 4, signal processors 2 ₁-2 _(L) firstdetermine whether the path timing of a finger has changed by x_(T) chipsor more (Step D1). The value x_(T) is the threshold value for the amountof change in path timing, and determines whether the rate of change inpath timing is at a level that cannot be followed by the weights thatare calculated by weight calculation units 6 ₁-6 _(L).

When the path timing of a finger equals or exceeds x_(T) chips, signalprocessors 2 ₁-2 _(L) use the initial weights that are generated byinitial weight generation units 9 ₁-9 _(L) in weighting/synthesizingcircuits 5 ₁-5 _(L) (Step D4). When the change in path timing of afinger falls short of x_(T) chips, signal processors 2 ₁-2 _(L)determine whether sufficient averaging time has been secured in signalcommon-mode average calculation units 13 ₁-13 _(L) and in time averagecalculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L)(Step D2).

If the averaging time of weight calculation units 6 ₁-6 _(L) is notsufficient, signal processors 2 ₁-2 _(L) use the initial weights of thefinger that have been generated by initial weight generation units 9 ₁-9_(L) in weighting/synthesizing circuits 5 ₁-5 _(L) (Step D4). On theother hand, if sufficient averaging time of weight calculation units 6₁-6 _(L) has been secured, signal processors 2 ₁-2 _(L) use the weightsof the finger that have been generated in time average calculation units15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L) inweighting/synthesizing circuits 5 ₁-5 _(L) (Step D3).

Generally, two methods are used in adaptive antennas for determining theinitial weight.

One method takes into consideration the point that the arrival directionof a user signal differs due to reception conditions, and takes as theinitial weight a value such as a non-directional weight that allowsreception regardless of the reception conditions in order to enablereception of the user signal under any conditions.

The other method is a method of estimating the initial weight based onsignals that are received by a plurality of antennas 1 ₁-1 _(N) (referto JP 2002-77011-A). In this method, the transmission path is estimatedbased on, for example, the received signals from each antenna, and thethus-obtained weight is taken as the initial weight.

The above-described methods of the prior art have the followingproblems:

When a non-directional weight is taken as the initial weight, gain isthe same for all directions, and as a result, a beam cannot be directedin the arrival direction of a desired user signal.

Using signals that are received by a plurality of antennas 1 ₁-1 _(N) toestimate the transmission path and then using the thus-obtained weightas the initial weight complicates highly accurate estimation of thetransmission path in a short time interval, and therefore preventsdirection of a beam in the arrival direction of a desired user signal.

As a result, when the path timing of a finger changes greatly at thetime a finger is newly assigned, or when sufficient averaging timecannot be secured in weight calculation units 6 ₁-6 _(L), there is apotential for degradation of the reception characteristics of the usersignal.

Using signals that are obtained by a plurality of antennas 1 ₁-1 _(N) toestimate the transmission path and then using the thus-obtained weightas the initial weight, not only entails a large amount of calculationfor estimating the transmission path, but also increases the burdenplaced on signal processors 2 ₁-2 _(L) and demands a high level ofprocessing capability.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an open-loopcontrolled adaptive antenna reception device that is capable of finding,in a short time interval, and moreover, with few computations, aninitial weight that allows reception of a user signal with superiorreception characteristics.

In an adaptive antenna reception device according to the presentinvention that can achieve the above-described object: a signalprocessor is assigned for at least one incoming wave, and in each signalprocessor, signals that are received by a plurality of antennas areweighted by weights of each antenna that are determined by using a timeaverage of a calculated value that is obtained by a prescribedcomputation from received signals by the plurality of antennas and thensynthesized to further synthesize a plurality of incoming waves thathave been received by the plurality of signal processors to obtain adesired signal.

In the adaptive antenna reception device of the present invention, aweight is determined by each signal processor in which at least aprescribed time interval is secured for the averaging time to find atime average, and based on these weights that have been determined, anarrival direction detection unit detects the arrival direction of anincoming wave that has been received by these signal processors. Areception quality acquisition unit then finds the reception quality ofthe signal of the incoming wave that has been received by weighting andsynthesizing by each signal processor in which at least a prescribedtime interval has been secured for the averaging time. An informationcollection/selection processor then, based on each arrival direction andthe reception quality of each arrival direction in each signal processorin which at least a prescribed time interval has been secured for theaveraging time, selects an initial beam direction in signal processorsthat are to begin determination of weight using time averaging.

Accordingly, the present invention, the initial beam direction of signalprocessors that are to begin determination of weight using a timeaverage can be selected based on the reception quality and the arrivaldirection of a high reliable incoming wave that is received at eachsignal processor in which a sufficient averaging time has been secured.As a result, a directional beam having excellent receptioncharacteristics can be quickly and easily obtained from the start.

In addition, the information collection/selection processor may select,from among a plurality of predetermined beam directions, the beamdirection that is closest to an arrival direction that has been detectedby, among signal processors in which at least a prescribed time intervalhas been secured for the averaging time, the signal processor in whichthe best reception quality has been obtained.

Accordingly, a plurality of beam directions that can be selected as theinitial beam direction can be determined in advance as a table, and thebeam direction that is closest to the arrival direction of the incomingwave having the best reception quality among each of incoming waves forwhich highly reliable reception quality has been measured and for whicha sufficient averaging time has been secured can be selected from amongthis plurality of beam directions. As a result, from the start adirectional beam having excellent reception quality can be obtained in ashort time interval and with little processing.

In addition, an initial weight generation unit may form a directionalbeam in the initial beam direction that has been selected by theinformation collection/selection processor and may find an initialweight that is used in weighting and synthesizing until an averagingtime of at least a prescribed time interval has been secured in signalprocessors.

Accordingly, in signal processors that are to begin determination ofweight that uses time averaging, a beam direction weight that isacquired quickly and easily can be used until sufficient averaging timehas been secured, and after the averaging time has become sufficient, ahighly accurate weight that is obtained by time averaging can be used.As a result, the appropriate method of determining beam direction can beselected according to the current conditions both before and aftersufficient averaging time has been secured, and a directional beamhaving good reception characteristics can always be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the configuration of anadaptive antenna reception device of the prior art,

FIG. 2 is a block diagram showing the configuration of aweighting/synthesizing circuit;

FIG. 3 is a flow chart showing operations when fingers in the adaptiveantenna reception device that is shown in FIG. 1 are assigned;

FIG. 4 is a flow chart showing operations when the path timing of afinger has changed in the adaptive antenna reception device that isshown in FIG. 1;

FIG. 5 is a block diagram showing an example of the configuration of anopen-loop controlled adaptive antenna reception device according to anembodiment of the present invention;

FIG. 6 shows an example of the reception of a signal by an antenna thatmakes up an adaptive antenna;

FIG. 7 shows the selection of, from among a plurality of beams that havebeen determined by an orthogonal multi-beam, a beam that is directed inthe direction that is closest to the arrival direction information ofthe finger in which the maximum SIR has been measured;

FIG. 8 shows the selection of, from among a plurality of beams that havebeen determined by equally spaced multi-beams, a beam that is directedin the direction that is closest to the arrival direction information ofthe finger in which the maximum SIR has been measured;

FIG. 9 is a table showing the weights of orthogonal or equally spacedmulti-beams;

FIG. 10 is a flow chart showing operations when assigning fingers in anadaptive antenna reception device according to the present embodiment;

FIG. 11 is a flow chart showing the operations when the path timing of afinger has changed in the adaptive antenna reception device according tothe present embodiment;

FIG. 12 is a block diagram showing an example of the configuration of anopen-loop controlled adaptive antenna reception device according toanother embodiment of the present invention; and

FIG. 13 is a block diagram showing an example of the configuration of anopen-loop controlled adaptive antenna reception device according to yetanother embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The following explanation regards the details of embodiments of thepresent invention with reference to the accompanying figures.

FIG. 5 is a block diagram showing an example of the configuration of anopen-loop controlled adaptive antenna reception device according to thepresent embodiment. In the adaptive antenna reception device of thepresent embodiment that is shown in FIG. 5, the number of antennas thatmake up the adaptive antenna is N (where N is an integer equal to orgreater than 2) and the number of synthesized multi-paths is L (where Lis a natural number). FIG. 5 shows the circuit portion for receiving theuser signal that is received from the mobile station of the k^(th) user(where k is a natural number).

Referring to FIG. 5, the adaptive antenna reception device includes:antennas 1 ₁-1 _(N), signal processors 2 ₁-2 _(L), adder 11, determiner12, searcher 16, and information collection/selection processor 22.

Signal processor 2 ₁ includes: delay unit 3 ₁, despreading circuits 4₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weight calculation unit6 ₁, transmission path estimation circuit 7 ₁, complex conjugate circuit8 ₁, initial weight generation unit 9 ₁, multiplier 10 ₁, arrivaldirection detection unit 20 ₁, and SIR measurement unit 21 ₁. Inaddition, weight calculation unit 6 ₁ includes: signal common-modeaverage calculation unit 13 ₁, correlation detection unit 14 ₁, and timeaverage calculation unit 15 ₁.

Although not shown in the figure, the interiors of signal processors 2₂-2 _(L) have the same configuration as signal processor 2 ₁. Forexample, signal processor 2 ₂ includes: delay unit 3 ₂, despreadingcircuits 4 ₂₁-4 _(2N), weighting/synthesizing circuit 5 ₂, weightcalculation unit 6 ₂, transmission path estimation circuit 7 ₂, complexconjugate circuit 8 ₂, initial weight generation unit 9 ₂, multiplier 10₂, arrival direction detection unit 20 ₂, and SIR measurement unit 21 ₂.Weight calculation unit 6 ₂ further includes signal common-mode averagecalculation unit 13 ₂, correlation detection unit 14 ₂, and time averagecalculation unit 15 ₂.

Searcher 16 uses each of the signals that are received at N antennas 1₁-1 _(N) to detect the delay times of L multi-paths. These delay timesare shown by, for example, the chip number. Searcher 16 then reports toeach of delay units 3 ₁-3 _(L), weight calculation units 6 ₁-6 _(L) andinitial weight generation units 9 ₁-9 _(L) of signal processors 2 ₁-2_(L) the timing information of the delay times that are used in each ofthese components. In addition, searcher 16 also reports the timinginformation of the delay times, that have been reported to all signalprocessors 2 ₁-2 _(L), to information collection/selection processor 22.

The assignment of fingers to signal processors 2 ₁-2 _(L) refers to theoperations by which searcher 16 reports the timing information of thedelay time of each multi-path to delay units 3 ₁-3 _(L) weightcalculation units 6 ₁-6 _(L), and initial weight generation units 9 ₁-9_(L) of each of signal processors 2 ₁-2 _(L) and starts signalprocessing operations.

In addition, the N antennas 1 ₁-1 _(N) are arranged in proximity so asto have high mutual correlation. The delay profiles of all N antennas 1₁-1 _(N) can be considered to be identical. Accordingly, the timinginformation of the delay times of each multi-path can be used in commonregardless of antennas 1 ₁-1 _(N).

Delay unit 3 ₁ delays each of the signals that have been received atantennas 1 ₁-1 _(N) in accordance with the timing information that hasbeen reported from searcher 16 and sends the delayed signals todespreading circuits 4 ₁₁-4 _(1N). Delay units 3 ₂-3 _(L) similarlydelay each of the signals that have been received at antennas 1 ₁-1 _(N)in accordance with the timing information that has been reported fromsearcher 16. Each of signal processors 2 ₁-2 _(L) is thus placed so asto correspond to the L multi-paths.

Despreading circuits 4 ₁₁-4 _(1N) subject each of the received signalsthat have been delayed at delay unit 3 ₁ to despreading, and send theresults to weighting/synthesizing circuit 5 ₁, weight calculation unit 6₁, and initial weight generation unit 9 ₁.

Weighting/synthesizing circuit 5 ₁ has the same configuration as thecomponent of the prior art that was shown in FIG. 2. Referring to FIG.2, weighting/synthesizing circuit 5, includes: multipliers 17 ₁-17 _(N),adder 18, and complex conjugate circuit 19 ₁-19 _(N).

Complex conjugate circuits 19 ₁-19 _(N) of weighting/synthesizingcircuit 5 ₁ generate each of the complex conjugates of the weights thathave been generated by weight calculation unit 6 ₁ or initial weightgeneration unit 9 ₁ and send the results to multipliers 17 ₁-17 _(N).Each of multipliers 17 ₁-17 _(N) multiplies the received signals, thathave been subjected to despreading by despreading circuits 4 ₁₁-4 _(1N),by the corresponding complex conjugates of the weights that have beengenerated by complex conjugate circuits 19 ₁-19 _(N) and sends theproducts to adder 18. Adder 18 synthesizes the outputs of multipliers 17₁-17 _(N) and sends the result to transmission path estimation circuit 7₁, multiplier 10 ₁, and SIR measurement unit 21 ₁ that are shown in FIG.5.

As described in the foregoing description, weighting/synthesizingcircuit 5 ₁ weights and synthesizes the signals from despreadingcircuits 4 ₁₁-4 _(1N).

Signal common-mode average calculation unit 13 ₁ of weight calculationunit 6 ₁ matches the phase of each symbol and performs vector addition(common-mode addition) of the symbols of signals that have undergonedespreading by despreading circuits 4 ₁₁-4 _(1N), finds the averagevalue of the signal for each antenna and sends the results tocorrelation detection unit 14 ₁. At this time, any number of symbols(the number of average symbols) may undergo common-mode addition. Inaddition, each symbol can be subjected to any weighting. The signalaverage value that is found by common-mode addition is a signal in whichthe SINR (Signal-to-Interference plus Noise Ratio: the ratio of thesignal power of a desired wave to the signal power of interference wavesand thermal noise power) has been improved.

When symbols that have undergone despreading have been subjected tomodulation, these symbols cannot be simply subjected to common-modeaddition. If a known pilot signal is used in such cases, the eliminationof modulation by the pilot symbol enables common-mode addition. Theeffect of SINR improvement increases as the number of average symbolsincreases, but when fluctuation in phase is extreme due to, for example,fading, the number of average symbols is limited.

Correlation detection unit 14 ₁ uses the average value of each signalfrom signal common-mode average calculation unit 13 ₁ to find thecorrelation value between the received signal at the antenna that is thereference and the received signals at other antennas. For this purpose,correlation detection unit 14 ₁ multiplies the complex conjugate of theaverage value of the signal, that corresponds to the reference antenna,with the average value of the signals that correspond to other antennas.Correlation detection unit 14 ₁ then sends the correlation values thatare the results of each multiplication to time average calculation unit15 ₁.

FIG. 6 shows an example of the reception of a signal by antennas 1 ₁-1_(N) that make up an adaptive antenna. In this example, antennas 1 ₁-1_(N) are arranged in one row at an equal spacing of element spacing d.

The advance in the phase of a signal that is received by each ofantennas 1 ₁-1 _(N) differs depending on the arrival direction of thesignal. For example, the phase of the signal that is received at antenna1 ₁ is advanced by (n−1)(2πd/π) sin θ₀ compared to the signal that isreceived at antenna 1 _(n) (where n is an integer 2≦n≦N). In this case,θ₀ is the angle of the arrival direction of the signal with respect tothe direction of arrangement of antennas 1 ₁-1 _(N). In addition, λ isthe wavelength of the carrier wave frequency.

Accordingly, if antenna 1 ₁ is taken as the reference antenna,−(n−1)(2πd/π) sin θ₀, which is the phase of the signal that is receivedat the n^(th) antenna 1 _(n), is ideally detected as the correlationvalue by correlation detection unit 14 ₁.

Time average calculation unit 15 ₁ takes the average of a prescribedtime interval for each correlation value that is obtained fromcorrelation detection unit 14 ₁ to find the weight for each of antennas1 ₁-1 _(N) and sends this weight to weighting/synthesizing circuit 5 ₁and arrival direction detection unit 20 ₁. The time interval foraveraging and the weighting method in time average calculation unit 15 ₁can assume a variety of forms, any of which can be selected.

In this way, weighting/synthesizing circuit 5 ₁ uses the weight that hasbeen generated by weight calculation unit 6 ₁ or the initial weight thatis generated by initial weight generation unit 9 ₁ to control andsynthesize the amplitude and phase of the signal that is received byantennas 1 ₁-1 _(N) and thus realize the directivity that allowsreception of a desired user signal at high gain.

The weighting for each of antennas 1 ₁-1 _(N) operates such that thephases of the received signals of each of antennas 1 ₁-1 _(N) for adesired signal that arrives from a direction of angle θ₀ are synthesizedby matching the phase of the received signal of antenna 1 ₁, which isthe reference antenna. For a signal that arrives from a direction thatdiffers from angle θ₀, the phase will not match between antenna 1 ₁,which is the reference antenna, and other antennas.

As a result, a beam is formed as the directivity of the array antenna,this beam having high gain in the direction of angle θ₀ but havingreduced gain in directions other than angle θ₀.

Transmission path estimation circuit 7 ₁ estimates the transmission pathdistortion based on the output signal of weighting/synthesizing circuit5 ₁ and sends the result to complex conjugate circuit 8 ₁.

Complex conjugate circuit 8 ₁ generates the complex conjugate of thetransmission path distortion that was estimated by transmission pathestimation circuit 7 ₁.

Multiplier 10 ₁ multiplies the complex conjugate of the transmissionpath distortion, that was generated by complex conjugate circuit 8 ₁, bythe output signal of weighting/synthesizing circuit 5 ₁ to compensatethe transmission path distortion.

Signals in which the transmission path distortion has been compensatedare similarly obtained from each of the fingers realized by signalprocessors 2 ₁-2 _(L).

Adder 11 implements rake synthesis by adding the output signals ofsignal processors 2 ₁-2 _(L) and sends the synthesis output signal todeterminer 12.

Determiner 12 determines each symbol and supplies the received symbolsof the k^(th) user as output.

Arrival direction detection units 20 ₁-20 _(L) find angle θ₀ of thearrival direction from the weights that have been generated by timeaverage calculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6_(L) and sends the result to information collection/selection processor22.

SIR measurement units 21 ₁-21 _(L) measure the SIR (Signal toInterference Ratio) that has been averaged over any time interval fromthe output of weighting/synthesizing circuits 5 ₁-5 _(L) and sends theresult to information collection/selection processor 22. The timeinterval over which this SIR has been averaged (the averaging time) ispreferably on the same order as the averaging time that is used insignal common-mode average calculation units 13 ₁-13 _(L) and timeaverage calculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6_(L). The averaging time is the time interval that is used for findingthe average for the variation value that is the object of averaging. Theaverage value in the averaging time of variation is found by averagingin the averaging time interval.

The timing information of each finger is applied as input from searcher16 to information collection/selection processor 22. In addition, SIRinformation from SIR measurement units 21 ₁-21 _(L) of signal processors2 ₁-2 _(L) for which fingers have already been assigned is furtherapplied as input to information collection/selection processor 22. Stillfurther, arrival direction information from arrival direction detectionunits 20 ₁-20 _(L) of signal processors 2 ₁-2 _(L), for which fingershave already been assigned and in which sufficient averaging time hasbeen secured in weight calculation units 6 ₁-6 _(L), is applied as inputto information collection/selection processor 22.

When searcher 16 newly assigns fingers to signal processors 2 ₁-2 _(L),when the path timings of the fingers that have been assigned to signalprocessors 2 ₁-2 _(L) undergo large changes, or when sufficientaveraging time has not been secured in signal common-mode averagecalculation units 13 ₁-13 _(L) and time average calculation units 15₁-15 _(L) of weight calculation units 6 ₁-6 _(L) of signal processors 2₁-2 _(L) for which fingers have already been assigned, informationcollection/selection processor 22 reports a beam number that is used ingenerating initial weights to initial weight generation units 9 ₁-9 _(L)of signal processors 2 ₁-2 _(L). The beam number that is reported atthis time is the beam number of the direction that is closest to thearrival direction of the signal in the finger (among the fingers thathave already been assigned to any of signal processors 2 ₁-2 _(L)) inwhich sufficient averaging time has been secured in signal common-modeaverage calculation units 13 ₁-13 _(L) and time average calculationunits 15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L) and for whichthe greatest SIR has been measured in SIR measurement units 21 ₁-21_(L). In addition, a plurality of beam numbers are determined in advanceusing multiple beams that are orthogonal or equally spaced with respectto the arrival direction of the signal, and informationcollection/selection processor 22 selects from among these beams a beamnumber that meets the above-described conditions.

FIG. 7 shows the selection, from among a plurality of beams that havebeen determined by orthogonal multi-beams, of the beam that is directedin the direction that is closest to the arrival direction information ofa finger in which the greatest SIR has been measured. In FIG. 7, thehorizontal axis is angle θ that indicates the beam direction, and thevertical axis is the amplitude. FIG. 7 shows the characteristics of aplurality of beams (in this case, M, where M is a natural number) thatcan be selected as the initial weight.

The directions of each of the orthogonal multi-beams that are shown inFIG. 7 are determined such that the peak direction of a particular beamwill be the null direction of other beams. If the arrival direction ofthe finger for which the maximum SIR is measured is angle θ₀, the beamof beam number m that is in the direction that is closest to thisdirection will be selected.

FIG. 8 shows the selection, from among a plurality of beams that havebeen determined by equally spaced multi-beams, of the beam directed inthe direction that is closest to the arrival direction information ofthe finger in which the greatest SIR has been measured. The direction ofthe equally spaced multi-beams that are shown in FIG. 8 is determinedsuch that the spacing of the beam directions is equal. If the arrivaldirection of the finger in which the greatest SIR is measured is θ₀, thebeam of beam number m that is closest to this direction will beselected, as in FIG. 7.

The arrival direction information of the finger in which the greatestSIR has been measured is used because the reception quality is verylikely to be high in the path of that beam direction of that finger. Inthe macro-cell environment of a mobile communication cellular system,the electric waves that are sent from a mobile station are reflected,diffracted, or scattered by the topography or structures such asbuildings in the vicinity of the mobile station and typically arrive ata radio base station by way of a plurality of paths having approximatelythe same arrival angle. As a result, it is appropriate to use the weightof the beam number of the beam that is closest to the arrival directioninformation of a finger that has been selected, as describedhereinabove, as the initial weight that is generated by initial weightgeneration units 9 ₁-9 _(L), In addition, the arrival directioninformation of the finger for which the maximum SIR has been measured isnot directly used in the generation of the initial weight. This isbecause it is believed that, in already assigned fingers, the arrivaldirection information of signal processors 2 ₁-2 _(L), in which themaximum SIR has been measured and in which sufficient averaging time hasbeen secured in signal common-mode average calculation units 13 ₁-13_(L) and in time average calculation units 15 ₁-15 _(L) of weightcalculation units 6 ₁-6 _(L), will differ from the signal arrivaldirection of fingers that have been newly assigned to signal processors2 ₁-2 _(L), fingers in which the timing has undergone large changes, orfingers in which sufficient averaging time has not been secured inweight calculation units 6 ₁-6 _(L) of signal processors 2 ₁-2 _(L) thathave been assigned.

Initial weight generation units 9 ₁-9 _(L) generate initial weights thatare used when weights of sufficient accuracy cannot be obtained byweight calculation units 6 ₁-6 _(L) and send these weights toweighting/synthesizing circuits 5 ₁-5 _(L).

Initial weight generation units 9 ₁-9 _(L) are used when searcher 16newly assigns fingers to signal processors 2 ₁-2 _(L) and sufficientaveraging time has not been secured in weight calculation units 6 ₁-6_(L) of signal processors 2 ₁-2 _(L) to which fingers have beenassigned. In addition, initial weight generation units 9 ₁-9 _(L) arealso used when the path timing of fingers that are in use undergo largechanges.

FIG. 9 is a table showing the weights of orthogonal or equally spacedmulti-beams. This table is used in the determination of weights byinitial weight generation units 9 ₁-9 _(L).

Referring to FIG. 9, weights are shown that correspond to beam numbers.Initial weight generation units 9 ₁-9 _(L) select the weights from thetable of FIG. 9 that correspond to beam number m that has been reportedby information collection/selection processor 22 and report theseweights to weighting/synthesizing circuits 5 ₁-5 _(L).

If there are no fingers in which sufficient averaging time has beensecured in weight calculation units 6 ₁-6 _(L) among fingers that havealready been assigned to signal processors 2 ₁-2 _(L), initial weightgeneration units 9 ₁-9 _(L) use a prescribed weight such as anondirectional weight or an estimated weight that is found bytransmission path estimation. A prescribed weight such as anondirectional weight or an estimated weight that is found bytransmission path estimation is referred to below as a second initialweight.

FIG. 10 is a flow chart showing the operations when fingers are assignedin an adaptive antenna reception device according to the presentembodiment. Referring to FIG. 10, information collection/selectionprocessor 22 first determines whether the fingers that have beenassigned to signal processors 2 ₁-2 _(L) by searcher 16 are new or not(Step A1). If the fingers are new, information collection/selectionprocessor 22 next determines whether there are fingers in whichsufficient averaging time has been secured in signal common-mode averagecalculation units 13 ₁-13 _(L) and time average calculation units 15₁-15 _(L) of weight calculation units 6 ₁-6 _(L) among the fingers thathave already been assigned to signal processors 2 ₁-2 _(L) (Step A6).

If there are no already existing fingers having sufficient averagingtime, information collection/selection processor 22 reports thissituation to initial weight generation units 9 ₁-9 _(L) of signalprocessors 2 ₁-2 _(L) to which new fingers have been assigned. Initialweight generation units 9 ₁-9 _(L) that receive this report generate asecond initial weight and send this weight to weighting/synthesizingcircuits 5 ₁-5 _(L). Weighting/synthesizing circuits 5 ₁-5 _(L) thathave received the second initial weight from initial weight generationunits 9 ₁-9 _(L) use this second initial weight to performweighting/synthesizing (Step A8).

If at least one already existing finger is determined to have sufficientaveraging time in the Step A6, information collection/selectionprocessor 22 reports the beam number of the beam, that is in thedirection closest to the signal arrival direction of the finger amongthese already existing fingers in which the highest SIR has beenmeasured, to initial weight generation units 9 ₁-9 _(L) of signalprocessors 2 ₁-2 _(L) to which new fingers have been assigned. Initialweight generation units 9 ₁-9 _(L) that have received this report selectfrom the table the initial weight that corresponds to this beam numberand send this initial weight to weighting/synthesizing circuits 5 ₁-5_(L). Weighting/synthesizing circuits 5 ₁-5 _(L) that have received theinitial weight from initial weight generation units 9 ₁-9 _(L) use thisinitial weight to realize weight synthesis (Step A7).

If the fingers are determined not to be new in the Step A1, informationcollection/selection processor 22 determines whether sufficientaveraging time has been secured in signal processors 2 ₁-2 _(L) to whichthese fingers have been assigned (Step A2).

If the averaging time is not sufficient, informationcollection/selection processor 22 determines whether there are fingersamong the fingers that have already been assigned to signal processors 2₁-2 _(L) in which sufficient averaging time has been secured in signalcommon-mode average calculation units 13 ₁-13 _(L) and in time averagecalculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L)(Step A4).

If at least one already existing finger has sufficient averaging time,the process advances to Step A7, and information collection/selectionprocessor 22 reports the beam number of the beam in the direction thatis closest to the signal arrival direction of the finger, among thealready existing fingers in which the highest SIR has been measured, toinitial weight generation units 9 ₁-9 _(L) of signal processors 2 ₁-2_(L) to which new fingers have been assigned. Initial weight generationunits 9 ₁-9 _(L) that receive this report select the initial weight thatcorresponds to this beam number from the table and send this initialweight to weighting/synthesizing circuits 5 ₁-5 _(L)Weighting/synthesizing circuits 5 ₁-5 _(L) that receive this initialweight from initial weight generation units 9 ₁-9 _(L) realizeweighting/synthesizing using this initial weight.

If there are no already existing fingers in which sufficient averagingtime has been secured in the Step A4, information collection/selectionprocessor 22 reports this finding to initial weight generation units 9₁-9 _(L) of signal processors 2 ₁-2 _(L) that are the objects of fingerassignment. Initial weight generation units 9 ₁-9 _(L) that receive thisreport generate a second initial weight and send this second initialweight to weighting/synthesizing circuits 5 ₁-5 _(L).

Weighting/synthesizing circuits 5 ₁-5 _(L) that receive the secondinitial weight from initial weight generation units 9 ₁-9 _(L) use thissecond initial weight to realize weighting/synthesizing (Step A5).

If sufficient averaging time is secured in the Step A2, weightcalculation units 6 ₁-6 _(L) of signal processors 2 ₁-2 _(L) that arethe objects of finger assignment send the calculated weight toweighting/synthesizing circuits 5 ₁-5 _(L). Weighting/synthesizingcircuits 5 ₁-5 _(L) that receive weights from weight calculation units 6₁-6 _(L) use these weights to realize weighting/synthesizing (Step A3).

FIG. 11 is a flow chart showing operations when the path timing offingers undergoes changes in the adaptive antenna reception deviceaccording to the present embodiment.

As shown in FIG. 11, in the event of a change of the path timing (delaytime) of a finger that has been assigned by searcher 16 to any of signalprocessors 2 ₁-2 _(L), information collection/selection processor 22determines whether the path timing of this finger has changed by morethan x_(T) chips (Step B1). Here, x_(T) chips is the threshold value forthe amount of change of path timing and is used to determine whether thechange in the path timing is at a level that cannot be followed by theweight that is calculated by weight calculation units 6 ₁-6 _(L) Whenthe change in path timing is greater than the threshold value, theweight from weight calculation units 6 ₁-6 _(L) cannot be relied uponuntil sufficient averaging time is secured.

If the change in path timing is equal to or greater than x_(T) chips,information collection/selection processor 22 next determines whetherthere are fingers among fingers that have already been assigned tosignal processors 2 ₁-2 _(L) in which sufficient averaging time has beensecured in signal common-mode average calculation units 13 ₁-13 _(L) andin time average calculation units 15 ₁-15 _(L) of weight calculationunits 6 ₁-6 _(L) (Step B6).

If there are not any already existing fingers in which sufficientaveraging time has been secured, information collection/selectionprocessor 22 reports this finding to initial weight generation units 9₁-9 _(L) of signal processors 2 ₁-2 _(L) that are the objects ofprocessing. Initial weight generation units 9 ₁-9 _(L) that receive thisreport generate the second initial weight and send this second initialweight to weighting/synthesizing circuits 5 ₁-5 _(L).Weighting/synthesizing circuits 5 ₁-5 _(L) that receive the secondinitial weight from initial weight generation units 9 ₁-9 _(L) use thissecond initial weight to realize weighting/synthesizing (Step B8).

If sufficient averaging time has been secured in at least one alreadyexisting finger in the Step B6, information collection/selectionprocessor 22 reports the beam number of the beam in the directionclosest to the signal arrival direction of the finger, among alreadyexisting fingers in which the highest SIR has been measured, to initialweight generation units 9 ₁-9 _(L) of signal processors 2 ₁-2 _(L) thatare the objects of processing. Initial weight generation units 9 ₁-9_(L) that receive this report select the initial weight that correspondsto this beam number from the table and send this initial weight toweighting/synthesizing circuits 5 ₁-5 _(L). Weighting/synthesizingcircuits 5 ₁-5 _(L) that have received the initial weight from initialweight generation units 9 ₁-9 _(L) use this initial weight to realizeweighting/synthesizing (Step B7).

If the change in path timing falls below XT chips in the Step B1,information collection/selection processor 22 determines whethersufficient averaging time has been secured in signal processors 2 ₁-2_(L) to which the fingers have been assigned (Step B2).

If the averaging time is not sufficient, informationcollection/selection processor 22 determines whether there are fingersamong fingers that have already been assigned to signal processors 2 ₁-2_(L) in which sufficient averaging time has been secured in signalcommon-mode average calculation units 13 ₁-13 _(L) and in time averagecalculation units 15 ₁-15 _(L) of weight calculation units 6 ₁-6 _(L)(Step B4).

If sufficient averaging time has been secured in at least one alreadyexisting finger, the process advances to Step B7, and informationcollection/selection processor 22 reports the beam number of the beam inthe direction closest to the signal arrival direction of the finger,among the already existing fingers in which the highest SIR has beenmeasured, to initial weight generation units 9 ₁-9 _(L) of signalprocessors 2 ₁-2 _(L) that are the objects of processing. Initial weightgeneration units 9 ₁-9 _(L) that receive this report select the initialweight that corresponds to this beam number from the table and send thisinitial weight to weighting/synthesizing circuits 5 ₁-5 _(L).Weighting/synthesizing circuits 5 ₁-5 _(L) that receive the initialweight from initial weight generation units 9 ₁-9 _(L) use this initialweight to realize weighting/synthesizing.

If there are no already existing fingers in which sufficient averagingtime has been secured in the Step B4, information collection/selectionprocessor 22 reports this finding to initial weight generation units 9₁-9 _(L) of signal processors 2 ₁-2 _(L) that are the object ofprocessing. Initial weight generation units 9 ₁-9 _(L) that receive thisreport generate a second initial weight and send this second initialweight to weighting/synthesizing circuits 5 ₁-5 _(L)Weighting/synthesizing circuits 5 ₁-5 _(L) that have received the secondinitial weight from initial weight generation units 9 ₁-9 _(L) use thesecond initial weight to realize weighting/synthesizing (Step B5).

If sufficient averaging time has been obtained in the Step B2, weightcalculation units 6 ₁-6 _(L) of signal processors 2 ₁-2 _(L) that arethe objects of processing send the calculated weight toweighting/synthesizing circuits 5 ₁-5 _(L). Weighting/synthesizingcircuits 5 ₁-5 _(L) that have received the weight from weightcalculation units 6 ₁-6 _(L) use this weight to realizeweighting/synthesizing (Step B3).

As described in the foregoing explanation, in an adaptive antenna thatforms beams for each finger according to the present embodiment, uponstabilization, accurate weights that have been calculated by weightcalculation units 6 ₁-6 _(L) are provided to weighting/synthesizingcircuits 5 ₁-5 _(L). However, when a finger is newly assigned, when thepath timing of the finger that is being assigned undergoes a greatchange, or when sufficient accuracy has not been obtained for the weightthat is calculated by weight calculation units 6 ₁-6 _(L) of an alreadyassigned finger, a beam is selected from a table that has a plurality ofbeams for which beam direction and weight have been determined inadvance as orthogonal or equally spaced multi-beams. This selected beamis the closest to the signal arrival direction of the finger having thegreatest SIR among other fingers for which sufficient averaging time hasbeen secured and weight of sufficient accuracy has been calculated. Byusing the weight of this selected beam as the initial weight, adirectional beam having high reception quality can be formed in a shorttime and with little calculation, and a deterioration of characteristicscan be prevented. This approach also allows a reduction of thevoluminous processing that is required when the transmission path isestimated and the weight that is obtained by this estimation is used asthe initial weight.

The following explanation regards another embodiment of the presentinvention.

FIG. 12 is a block diagram showing an example of the configuration ofthe open-loop controlled adaptive antenna reception device according toanother embodiment of the present invention. As with the device that isshown in FIG. 5, in the adaptive antenna reception device that is shownin FIG. 12, N is the number of antennas that make up the adaptiveantenna (where N is an integer equal to or greater than 2) and L is thenumber of multi-paths that are synthesized (where L is a naturalnumber). In addition, the figure shows the circuit portion that receivesthe user signal from the mobile station of the k^(th) user (where k is anatural number).

Referring to FIG. 12, the adaptive antenna reception device includes:antennas 1 ₁-1 _(N), signal processors 23 ₁-23 _(L), adder 11,determiner 12, searcher 16, and information collection/selectionprocessor 22.

Signal processor 23 ₁ includes: delay unit 3 ₁, despreading circuits 4₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weight calculation unit6 ₁, transmission path estimation circuit 7 ₁, complex conjugate circuit8 ₁, initial weight generation unit 9 ₁, multiplier 10 ₁, arrivaldirection detection unit 20 ₁, and signal power measurement unit 24 ₁.In addition, weight calculation unit 6 ₁ includes: signal common-modeaverage calculation unit 13 ₁, correlation detection unit 14 ₁, and timeaverage calculation unit 15 ₁.

Although not shown in the figure, the interiors of signal processors 23₂-23 _(L) have the same configuration as signal processor 23 ₁. Forexample, signal processor 23 ₂ includes: delay unit 3 ₂, despreadingcircuits 4 ₂₁-4 _(2N), weighting/synthesizing circuit 5 ₂, weightcalculation unit 6 ₂, transmission path estimation circuit 7 ₂, complexconjugate circuit 8 ₂, initial weight generation unit 9 ₂, multiplier 10₂, arrival direction detection unit 20 ₂, and signal power measurementunit 24 ₂. In addition, weight calculation unit 6 ₂ includes: signalcommon-mode average calculation unit 13 ₂, correlation detection unit 14₂, and time average calculation unit 15 ₂.

Antennas 1 ₁-1 _(N), adder 11, determiner 12, searcher 16, informationcollection/selection processor 22, delay unit 3 ₁, despreading circuits4 ₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weight calculationunit 6 ₁, transmission path estimation circuit 7 ₁, complex conjugatecircuit 8 ₁, initial weight generation unit 9 ₁, multiplier 10 ₁, andarrival direction detection unit 20 ₁ are all identical to the elementsshown in FIG. 5. The two configurations differ in that SIR measurementunits 21 ₁-21 _(L) in FIG. 5 are replaced by signal power measurementunits 24 ₁-24 _(L) in FIG. 12.

Signal power measurement units 24 ₁-24 _(L) measure any time averagedsignal power based on the output of weighting/synthesizing circuits 5₁-5 _(L) and sends the result to information collection/selectionprocessor 22. When sufficient accuracy has not been obtained in theweights that are calculated by weight calculation units 6 ₁-6 _(L),information collection/selection processor 22 reports the beam numberthat is used in generating initial weights to initial weight generationunits 9 ₁-9 _(L) of these signal processors 23 ₁-23 _(L). In the presentembodiment, the beam number that is reported at this time is the beamnumber of the direction that is closest to the arrival direction of thesignal in, among fingers that have already been assigned to any ofsignal processors 23 ₁-23 _(L), the finger in which sufficient averagingtime has been secured in signal common-mode average calculation units 13₁-13 _(L) and time average calculation units 15 ₁-15 _(L) of weightcalculation units 6 ₁-6 _(L) and in which the greatest signal power hasbeen measured in signal power measurement units 24 ₁-24 _(L). Aplurality of beam numbers have been determined in advance usingmulti-beams that are orthogonal or equally spaced with respect to thearrival direction of the signal, as shown in FIGS. 7 and 8.

In the present embodiment, attention is focused on the high probabilitythat the received signal of a path having high signal power will haveexcellent characteristics. Accordingly, the beam that is selected is thebeam closest to the signal arrival direction of, among fingers in whichsufficient averaging time has been secured and weights of sufficientaccuracy have been calculated, the finger in which the received signalpower is a maximum. As a result, as with the device that is shown inFIG. 5, a directional beam having high reception quality can be formedin a short time and with few operations and degradation ofcharacteristics can be prevented. In addition, the present embodimentcan reduce the large amount of processing that is required whentransmission path estimation is carried out and the thus-obtained weightis used as the initial weight.

The following explanation regards yet another embodiment of the presentinvention.

FIG. 13 is a block diagram showing an example of the configuration of anopen-loop controlled adaptive antenna reception device according to yetanother embodiment of the present invention. As with the devices thatare shown in FIG. 5 and FIG. 12, in the adaptive antenna receptiondevice that is shown in FIG. 13, N is the number of antennas that makeup the adaptive antenna (where N is an integer that is equal to orgreater than 2), and L is the number of synthesized multi-paths (where Lis a natural number). The figure shows the circuit portions forreceiving the user signal that is received from the mobile station ofthe k^(th) user (where k is a natural number).

Referring to FIG. 13, the adaptive antenna reception device includes:antennas 1 ₁-1 _(N), signal processors 25 ₁-25 _(L), adder 11,determiner 12, searcher 16, path timing comparator 26, and informationcollection/selection processor 22.

Signal processor 25 ₁ includes: delay unit 3 ₁, despreading circuits 4₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weight calculation unit6 ₁, transmission path estimation circuit 7 ₁ complex conjugate circuit8 ₁, initial weight generation unit 9 ₁, multiplier 10 ₁, and arrivaldirection detection unit 20 ₁. In addition, weight calculation unit 6,includes signal common-mode average calculation unit 13 ₁, correlationdetection unit 14 ₁, and time average calculation unit 15 ₁.

Although not shown in the figure, the interiors of signal processors 25₂-25 _(L) have the same configuration as signal processor 25 ₁.

Antennas 1 ₁-1 _(N), adder 11, determiner 12, searcher 16, informationcollection/selection processor 22, delay unit 3 ₁, despreading circuits4 ₁₁-4 _(1N), weighting/synthesizing circuit 5 ₁, weight calculationunit 6 ₁, transmission path estimation circuit 7 ₁, complex conjugatecircuit 8 ₁, initial weight generation unit 9 ₁, multiplier 10 ₁, andarrival direction detection unit 20 ₁ are identical to the elementsshown in FIG. 5.

The adaptive antenna reception device of the present embodiment shown inFIG. 13 lacks SIR measurement units 21 ₁-21 _(L) that are shown in FIG.5 but includes path timing comparator 26.

Based on the timing information from searcher 16, path timing comparator26 reports the finger having the shortest delay time to informationcollection/selection processor 22.

Information collection/selection processor 22 reports the beam numberthat is used in generating the initial weights to initial weightgeneration units 9 ₁-9 _(L) of signal processors 25 ₁-25 _(L) whensufficient accuracy is not obtained in the weights that are calculatedin weight calculation units 6 ₁-6 _(L) In the present embodiment, thebeam number that is reported at this time is the beam number of thedirection that is closest to the arrival direction of the signal in,among the fingers that have already been assigned to any of signalprocessors 25 ₁-25 _(L), the finger in which the delay time is shortestand in which sufficient averaging time has been secured in signalcommon-mode average calculation units 13 ₁-13 _(L) and time averagecalculation units 15 ₁-15 _(L) in weight calculation units 6 ₁-6 _(L).In this case, a plurality of beam numbers have been determined inadvance using multi-beams that are orthogonal or equally spaced withrespect to the arrival direction of the signal, as shown in FIGS. 7 and8.

In the present embodiment, attentions focuses on the high probabilitythat the signal that is received on the path having the shortest delaytime is a direct wave having a high reception level and superiorreception characteristics. Accordingly, a beam is selected that isclosest to the signal arrival direction of, among fingers in whichsufficient averaging time has been secured and in which weights havebeen calculated with sufficient accuracy, the finger that has theshortest delay time. As a result, as with the device that is shown inFIG. 5, a directional beam having high reception quality can be formedin a short time and with little calculation, and degradation ofcharacteristics can be prevented. In addition, the present embodimentallows a reduction of the large amount of processing that was requiredwhen carrying out a transmission path estimation and using thethus-obtained weight as the initial weight.

In addition, although the signal arrival direction of the finger havingthe shortest delay time was used in the present embodiment, as anotherexample, the signal arrival direction of the finger in which thecontinuous time of the path is longest may also be used. The continuoustime of the path is the time during which an incoming wave iscontinuously received without being interrupted by signal processors 25₁-25 _(L). In this case, attention is given to the high probability thatthe signal that is received by the path having the longest continuoustime is the most stable direct wave.

All of the embodiments that have been described thus far involvedexamples of devices that were used in CDMA communication, but thepresent invention is not limited to this CDMA form. As an example, thepresent invention can also be applied to devices that are used in TDMA(Time Division Multiple Access) or FDMA (Frequency Division MultipleAccess) communication.

In addition, examples have been presented in all of the embodimentsdescribed thus far in which a method was used in weight calculationunits 6 ₁-6 _(L) for simply estimating the arrival direction of adesired wave, but the present invention is not limited to algorithmsthat are used in weight calculation units 6 ₁-6 _(L). For example, anarrival direction estimation algorithm realized by a MUSIC algorithm orESPRIT algorithm may also be used.

1. An adaptive antenna reception method wherein a signal processor isassigned to at least one incoming wave, and in said signal processor,signals that are received by a plurality of antennas are weighted byweights of each of said antennas that are determined by using a timeaverage of a calculated value that is obtained by a prescribedcomputation from received signals of said plurality of antennas and thensynthesized to further synthesize a plurality of incoming waves that arereceived in a plurality of signal processors to obtain a desired signal;said adaptive antenna reception method comprising steps of: a first stepfor detecting the arrival direction of an incoming wave that is receivedby signal processors from weights that are determined by each signalprocessor in which at least a prescribed time interval has been securedfor an averaging time to find a time average; a second step for findingthe reception quality of the signal of an incoming wave that is receivedby weighting and synthesizing by each of said signal processors in whichat least said prescribed time interval has been secured for theaveraging time; and a third step for selecting an initial beam directionin said signal processors that are to begin determination of weightsusing time averages, based on each arrival direction and the receptionquality in each of said signal processors in which at least saidprescribed time interval has been secured for averaging time.
 2. Theadaptive antenna reception method according to claim 1, wherein, in saidthird step, the beam direction that is closest to the arrival directionthat has been detected in, among each of said signal processors in whichat least said prescribed time interval has been secured for saidaveraging time, the signal processor in which the best reception qualityhas been obtained is selected from among a plurality of predeterminedbeam directions.
 3. The adaptive antenna reception method according toclaim 1, wherein, in said second step, the ratio of the signal power ofa desired wave to the signal power of interference waves is measured assaid reception quality.
 4. The adaptive antenna reception methodaccording to claim 1, wherein, in said second step, signal power ismeasured as said reception quality.
 5. The adaptive antenna receptionmethod according to claim 1, wherein, in said second step, delay time isused as said reception quality.
 6. The adaptive antenna reception methodaccording to claim 1, wherein, in said second step, the continuous timeof a path is used as said reception quality.
 7. The adaptive antennareception method according to claim 1, further comprising a fourth stepfor finding an initial weight to form a directional beam in an initialbeam direction that is selected in said third step, and using thisinitial weight in weighting and synthesizing until at least a prescribedtime interval has been secured for averaging time in said signalprocessors.
 8. An adaptive antenna reception device, in which a signalprocessor is assigned to at least one incoming wave, and in said signalprocessor, signals that are received by a plurality of antennas areweighted by weights of each of said antennas that are determined byusing a time average of a calculated value that is obtained by aprescribed computation from received signals of said plurality ofantennas and then synthesized to further synthesize a plurality ofincoming waves that have been received in a plurality of signalprocessors to obtain a desired signal; said adaptive antenna receptiondevice comprising: an arrival direction detection unit for detecting thearrival direction of an incoming wave that is received by the signalprocessors from weights that have been determined by each signalprocessor in which at least a prescribed time interval has been securedfor averaging time to find a time average; a reception qualityacquisition unit for finding reception quality of a signal of anincoming wave that is received by weighting and synthesizing by each ofsaid signal processors in which at least said prescribed time intervalhas been secured for averaging time; and an informationcollection/selection processor for selecting an initial beam directionin said signal processors that are to begin determination of weightsthat uses time average, based on each arrival direction and thereception quality in each of said signal processors in which at leastsaid prescribed time interval has been secured for averaging time. 9.The adaptive antenna reception device according to claim 8, wherein saidinformation collection/selection processor selects, from among aplurality of predetermined beam directions, the beam direction that isclosest to an arrival direction that has been detected by, among each ofsaid signal processors in which at least said prescribed time intervalhas been secured for said averaging time, the signal processor in whichthe best reception quality has been obtained.
 10. The adaptive antennareception device according to claim 8, wherein said reception qualityacquisition unit measures the ratio of the signal power of a desiredwave to the signal power of interference waves as said receptionquality.
 11. The adaptive antenna reception device according to claim 8,wherein said reception quality acquisition unit measures signal power assaid reception quality.
 12. The adaptive antenna reception deviceaccording to claim 8, wherein said reception quality acquisition unituses delay time as said reception quality.
 13. The adaptive antennareception device according to claim 8, wherein said reception qualityacquisition unit uses continuous time of a path as said receptionquality.
 14. The adaptive antenna reception device according to claim 8,further comprising an initial weight generation unit for forming adirectional beam in an initial beam direction that has been selected bysaid information collection/selection processor and for finding aninitial weight that is used in weighting and synthesizing until at leastsaid prescribed time interval has been secured for averaging time insaid signal processors.
 15. The adaptive antenna reception methodaccording to claim 2, wherein, in said second step, the ratio of thesignal power of a desired wave to the signal power of interference wavesis measured as said reception quality.
 16. The adaptive antennareception method according to claim 2, wherein, in said second step,signal power is measured as said reception quality.
 17. The adaptiveantenna reception method according to claim 2, wherein, in said secondstep, delay time is used as said reception quality.
 18. The adaptiveantenna reception method according to claim 2, wherein, in said secondstep, the continuous time of a path is used as said reception quality.19. The adaptive antenna reception device according to claim 9, whereinsaid reception quality acquisition unit measures the ratio of the signalpower of a desired wave to the signal power of interference waves assaid reception quality.
 20. The adaptive antenna reception deviceaccording to claim 9, wherein said reception quality acquisition unitmeasures signal power as said reception quality.
 21. The adaptiveantenna reception device according to claim 9, wherein said receptionquality acquisition unit uses delay time as said reception quality. 22.The adaptive antenna reception device according to claim 9, wherein saidreception quality acquisition unit uses continuous time of a path assaid reception quality.